The present invention relates to a motor current detection apparatus to detect a current flowing in a brushless motor, a motor controller to control the brushless motor using the current detected by the motor current detection apparatus, and an electric power tool which is provided with a brushless motor as a drive source.
There is a known electric power tool which is provided with a protection function to protect the motor from overcurrent. A specific example of such protection function against overcurrent is disclosed in Japanese Unexamined Patent Application Publication No. 2001-103788. Specifically, there is disclosed a technique to detect a current flowing in a motor through an integration circuit, and restrict current conduction to the motor in a case where a first overcurrent (for example, 1.8 times of a rated current) flows, or in a case where a second overcurrent (for example, 1.5 times of a rated current), which is lower than the first overcurrent, continuously flows for a predetermined time period (for example, 3 seconds).